Ph.D. student eying effectiveness of occupancy-based HVAC system

Simge Andolsun

Significant energy savings could be realized
in small, approximately 1,000 square foot homes in hot climates with an air
conditioning system being researched by Simge Andolsun, a Ph.D. architecture
student at Texas A&M, that cools rooms based on where people are at
different times during the day.

“Residential energy cost is a
significant burden, particularly for low-income households,” she said. “A total
of 38.6 million households are in need of low-income home energy assistance in
the U.S., and Texas ranks second in the nation in the number of housing units
eligible for low-income home energy assistance.”

Andolsun is researching the system
with a $15,000 dissertation fellowship from Texas A&M’s Office of Graduate
Studies, a $10,000 graduate student-in-aid grant from the American Society of
Heating, Refrigerating and Air-Conditioning Engineers and support from Texas
A&M’s Energy Systems Lab, where she is a research assistant.

She is studying applications of two
concepts, developed by her faculty advisor, Charles Culp, professor of
architecture and ESL associate director, that could provide a 30- to 50-percent
reduction in energy costs in hot and humid climates in the U.S.: “partial
conditioning of space,” in which only rooms in use are cooled with conditioned
air, which is also used to partially condition unoccupied rooms, and “partial
use of space” — for example, an unconditioned atrium is comfortable for use
much of the year because it uses conditioned air from other spaces.

The “partial conditioning” heating, ventilation and air
conditioning system that Andolsun is researching pulls in outside air,
conditions it and routes it, during overnight hours for
instance, first to bedrooms, then from the bedroom to the currently unoccupied living
room.

Andolsun visited a Habitat for Humanity
house in Bryan to gather data to design a baseline virtual residence for the
study and is using a second virtual residence, based on the Bryan residence
design, modified with a “partial conditioning” HVAC system and an atrium to
test the “partial use of space” concept.

Comparing the energy use of the two houses
with energy modeling tools, she will reference her findings to create design
guidelines for residential HVAC design in hot and humid climates.

“How much energy will be needed to
move the air to unoccupied zones? How much air should be sent? Do we use a
controlled airflow? Do we move the cool air with a fan, or will the air move
with its own flow? How much money would such a system save? These are some of
the questions the study will address,” said Andolsun.

“Implementing these concepts could improve
people’s health because more fresh air gets to where they actually are in the
house, depending on the time of day, instead of what is done today, which is
recirculate inside air and let fresh air leak in from outside,” said Culp.